<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <button>点击</button>
    <script>
        const button = document.querySelector("button")
        button.onclick = function () {
            console.log("hello JavaScript");
        }
        //解绑事件
        button.onclick = null
    </script>
</body>

</html>